content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * ------------------------
   * DefaultValueDataset.java
   * ------------------------
   * (C) Copyright 2003-2012, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 27-Mar-2003 : Version 1 (DG);
   * 18-Aug-2003 : Implemented Cloneable (DG);
   * 03-Mar-2005 : Implemented PublicCloneable (DG);
   * ------------- JFREECHART 1.0.x ---------------------------------------------
   * 30-Jan-2007 : Added explicit super() call in constructor (for clarity) (DG);
   * 17-Jun-2012 : Removed JCommon dependencies (DG);
   *
   */
  
  package org.jfree.data.general;
  
  import java.io.Serializable;
  
  import org.jfree.chart.util.ObjectUtilities;
  import org.jfree.chart.util.PublicCloneable;
  
  /**
   * A dataset that stores a single value (that is possibly <code>null</code>).
   * This class provides a default implementation of the {@link ValueDataset}
   * interface.
   */
  public class DefaultValueDataset extends AbstractDataset
          implements ValueDataset, Cloneable, PublicCloneable, Serializable {
  
      /** For serialization. */
      private static final long serialVersionUID = 8137521217249294891L;
  
      /** The value. */
      private Number value;
  
      /**
       * Constructs a new dataset, initially empty.
       */
      public DefaultValueDataset() {
          this(null);
      }
  
      /**
       * Creates a new dataset with the specified value.
       *
       * @param value  the value.
       */
      public DefaultValueDataset(double value) {
          this(new Double(value));
      }
  
      /**
       * Creates a new dataset with the specified value.
       *
       * @param value  the initial value (<code>null</code> permitted).
       */
      public DefaultValueDataset(Number value) {
          super();
          this.value = value;
      }
  
      /**
       * Returns the value.
       *
       * @return The value (possibly <code>null</code>).
       */
      @Override
      public Number getValue() {
          return this.value;
      }
  
      /**
       * Sets the value and sends a {@link DatasetChangeEvent} to all registered
       * listeners.
       *
       * @param value  the new value (<code>null</code> permitted).
       */
      public void setValue(Number value) {
          this.value = value;
          notifyListeners(new DatasetChangeEvent(this, this));
      }
  
      /**
       * Tests this dataset for equality with an arbitrary object.
       *
       * @param obj  the object (<code>null</code> permitted).
       *
       * @return A boolean.
       */
      @Override
      public boolean equals(Object obj) {
          if (obj == this) {
              return true;
          }
          if (obj instanceof ValueDataset) {
              ValueDataset vd = (ValueDataset) obj;
              return ObjectUtilities.equal(this.value, vd.getValue());
          }
          return false;
      }
  
      /**
       * Returns a hash code.
       *
       * @return A hash code.
       */
      @Override
      public int hashCode() {
          return (this.value != null ? this.value.hashCode() : 0);
      }
  
  }
  